Hafida Gaspard

Asymmetric synthesis and biological evaluation of natural or bioinspired cytotoxic C2-symmetrical lipids with two terminal chiral alkynylcarbinol pharmacophores.

Bidirectional syntheses of C2-symmetrical lipids embedding two terminal alkynylcarbinol pharmacophores are reported. Naturally occurring chiral alkenylalkynylcarbinol units were generated using Pus procedure for enantioselective addition of terminal alkynes to aldehydes, allowing the first asymmetric synthesis of (3R,4E,16E,18R)-icosa-4,16-diene-1,19-diyne-3,18-diol, isolated from Callyspongia pseudoreticulata. Two synthetic analogues embedding the recently uncovered (S)-dialkynylcarbinol pharmacophore were secured using Carreiras procedure adapted to ynal substrates. The dramatic effect of the carbinol configuration on cytotoxicity was confirmed with submicromolar IC50 values against HCT116 cells.

Bismuth (III) salts in friedel-crafts acylation

Publisher Summary This chapter illustrates that while bismuth chloride is an efficient catalyst for the aromatic ether acylation by acid chlorides or anhydrides, it is not strong enough to carry out the acylation of non activated aromatics. However, the potential of using a wide range of Bi salts as catalysts, in particular the oxide, the oxychloride and the carboxylates, all non hygroscopic compounds, offers advantages, and is indicative of the great versatility of Bi derivatives. Moreover, the Bi salts obtained after hydrolytic workup are directly reusable. The para-selectivity of the described acylations is very high. In the case of the bismuth salt, the ortho effect, with its disadvantages, does not appear. Because the molecular chemistry is well developed, it seems possible to undertake the synthesis and study of the catalytic power of new bismuth derivatives containing suitable ligands to activate the Lewis acidity of this element.

Skeletal Optimization of Cytotoxic Lipidic Dialkynylcarbinols

In line with a recent study of the pharmacological potential of bioinspired synthetic acetylenic lipids, after identification of the terminal dialkynylcarbinol (DAC) and butadiynyl alkynylcarbinol (BAC) moieties as functional antitumor pharmacophoric units, this work specifically addresses the issue of carbon backbone length. A systematic variation of the aliphatic chain length was thus carried out in both the DAC and BAC series. The critical impact of the length of the lipidic skeleton was first confirmed in the racemic series, with the highest cytotoxic activity observed for C17 to C18 backbones. Enantiomerically enriched samples were prepared by asymmetric synthesis of the optimal C18 DAC and C17 BAC derivatives. Samples with upgraded enantiomeric purity were alternatively produced by enzymatic kinetic resolution. Eutomers possessing the S configuration displayed cytotoxicity IC50 values as low as 15 nm against HCT116 cancer cells, the highest level of activity reached to date in this series.